Forecaster summary - Issued 2021-03-27T00:29:46

The high energy electron flux (greater than 2 MeV) is generally expected to be at normal background to moderate levels over the next couple of days, with a chance of temporarily exceeding the high threshold at diurnal max. Then there is an increased chance of reaching high levels again from day 3 (29th March), following the arrival of a high speed stream from coronal hole 37. The corresponding 24-hour electron fluence is expected to remain below the Active threshold for most of the period, then increasing closer to, or possibly above the Active threshold by day 3 or 4 (29-30th March). By day 4 (30th March) although electron flux levels are likely to be moderate to high, the arrival of coronal hole 36 may suppress values later.

The Met Office REFM model is considered to be offering good guidance, in that the Active threshold is not reached during days 1-2. However, a greater increasing trend in the fluence is possible by day 3 (29th March), which is not indicated by the model at this time. The risk of Active fluence remains steady for much of day 4 (30th March) but reduces with the likely arrival of the high-speed stream from coronal hole 36.